Tube mill and means for lubrication



Mar'cH 24, I953 J. E. KENNEDY 2,632,529

TUBE MILL AND MEANS FOR LUBRICATION Original Filed June 20, 1945 2 SHEETS-SHEET l 13 INVENTOR 4 wsep 2 zYwneqiy March 24, 1953 J. E. KENNEDY TUBE MILL AND MEANS FOR LUBRICATION 2 SHEETS-SHEET 2 Original Filed June20, 1945 I the mill.

Patented Mar. 24, 1953 UNITED STATES ATENT OFFICE TUBE MILL AND MEANS FOR LUBRICATION Joseph E. Kennedy, New York, N. Y.

Original application June 20, 1945, Serial 'No.

2 Claims. 1

This invention relates to improvements in tube mills such as those of the rotary drum type in which tubes, rods, balls, etc., are used as grinding elements to pulverize coal and other materials.

More particularly, the present invention relates to tube mills of the very large or heavy type in which the drum has a diameter of the order of ten feet, and in which a heavy double reducing gear system is employed for rotating the drum.

This application is a division of my pending application Serial No. 600,561, filed June 20, 1945, for Improved Tube Mill, now Patent Number Largetube mills of the type under consideration are presently employed in grinding units for producing pulverized or powdered coal which is burned in large steam generator units and other industrial equipment. In these installations the coal is fed into the mill through a follow trunnion which serves as one of the end bearings for themill. The coal is pulverized in the rotary drum by means of rods, balls or other grinding elements, and during this operation the mill is swept by an air stream which picks up the dust or pulverized material and carries it through a hollow trunnion at the opposite end of the drum which also serves as a bearing for the rotation of The air stream containing the pulverized coal for example, is sent to a separator or directly to burners. In mills of this type, one of the trunnions serves as an anchor for a gear wheel of the gear system for driving the drum, and the rotary trunnion is sealed with respect to agear casing mounted around the gears to exclude the dust produced in the grinding opera tions. The gears are commonly lubricated by having them dip into bodies of lubricating oil in the casing."

A number of problems has arisen in connection with the operation of these heavy tube mills, one of which relates to the starting of the mill. Anyone familiar with this art will understand that a large rotary drum of the type referred to, having a heavy lining of wear-resisting material and also containing a substantial weight of loose grinding elements, will be extremely difficult to start. An electric motor of high horse-power is capable of starting the rotation of the drum because of the great leverage provided by the reducing gear system employed. However, the gears have been severely damaged in certain instances because of the lack of lubricant at the points of contact when the rotation of the drum is started. The gears of such a mill are very expensive and diflicult to make and in most cases a Divided and this application August 19, 1948, Serial No. 45,073

2 shut-down for replacement or repair becomes very serious.

The provision of clutches and gear shifts for avoiding the troubles involved in starting the rotation of the drum has not been successfuL'apparently because of the very heavy starting loads involved. Other problems are involved in obtaining uniformly fine pulverized coal.

The primary object of the present invention is, therefore, to provide an improved tube mill in which the difficulties involved in the starting operation are avoided by a relatively simple arrangement.

A further object of the invention is to provide an improved lubricating system or procedure for facilitating the starting of the mill without damaging the gears.

According to the features of the present invention, the improved tube mill which includes a rotary drum containing loose grinding elements and a reduction gear system for rotating the drum, comprises means for maintaining a reservoir of lubricant in a casing surrounding the gear system, means for forcing lubricant from said reservoir through suitable distributing pipes and for spraying the lubricant onto inter-meshing gears of the gear system at the point where the gear teeth of any two inter-meshing gears approach each other upon their rotation, and means for supplying lubricant to the trunnion bearing which is also surrounded by the gear casing.

An important feature of the present invention is the method and means for starting the mill in which means is provided for forcing lubricating oil from the oil reservoir onto the gears, as de: scribed above, for a time sufiicient to thoroughly lubricate the gears prior to the starting of the mill.

The improved tube mill of the present invention includes other features of importance which will be described in detail in connection with the accompanying drawings forming a part of this application. V

In the drawings:

Fig 1 is a perspective view of the mill of the present invention showing the relationship of some of the parts, with other parts removed.

Fig. 2 is a plan view partly in section of a portion of one end of the mill with parts broken away, showing the relationship of the various gears for driving the mill and the lines for lubrieating the gears in accordance with the present invention. 7

Fig. 3 is a broken side elevational view partly in section, showing the detailed construction of both ends of the mill and the details of the improved means for lubricating the bearings and ears and for sealing the gear case with respect to the rotary trunnion.

Fig. 4 is a detailed broken vertical sectional view of a preferred form of bearing construction.

Referring to the drawings which are partly diagrammatic, the improved mill of the present invention is shown in general outline in Fig. 1. The mill comprises a large rotary drum 5% mounted for rotation at one end on a support 82 and at the other end on a support 54, including a heavy casting forming the lower portion of the gear casing. The support M, as well as certain other elements of the apparatus, is mounted upon a heavy reinforced foundation iii. The apparatus, for pulverizing or grinding coal and all kinds of materials, of the type shown, is of very large diameter. For example, the drum ill may have. a diameter between ten and eleven feet and would include a heavy lining of wear-resisting material.

of the type commonly used in such equipment. In Fig. 1 the gear casing in addition to comprising a part of the support 24 also includes a cover section it sealed thereto in a dustproof manner. The gears for driving the drum H1 preferably comprise a double reduction gear set, shown more in detail in Figs. 2 and 3, and which are preferably driven by an electric motor 20 of suitable high horse-power, although other power means may be used.

7 An important feature of the apparatus of the present invention comprises means for suitably lubricating the driving gears and main trunnion bearing mounted in the gear casing. This means includes a cylinder pump 22 driven by an electric motor 2 through suitable driving means. The pump draws lubricating oil from an oil reservoir in the lower portion of the gear casing 16 (Fig. 3), through a line 28, and forces the oil through a valved discharge line 28, provided with a valve 29 to the various critical points to be lubricated. Lubricant is forced through branch lines 30, 32, 34, 35 and others, if desired, the lines 3 3 and 32 terminating in nozzles which discharge at the points at which gears inter-mesh, while the lines 3 2 and 35 supply lubricant respectively to the upper and lower portions of the trunnion bearing.

An important feature of the invention resides in the arrangement for lubricating the critical points of the driving mechanism prior to the actual starting of the apparatus. For example, when it is desired to start up the apparatus, the

motor 24 is started and runs for a minute or more to build up sufficient pressure in the lines 35, 32, 3d and 35, to thoroughly lubricate the gear elements and bearing surfaces which come in contact first. After the lapse of the desired time for accomplishing this object, the motor 28 is started, and since the gears and trunnion hearing have been previously lubricated, damage of the gears by the heavy starting load will be prevented. The motors 24 and 243 are started by separate switches and by hand, if desired, but the entire apparatus may be conveniently started by a starting switch which initiates the operation of the motor 24 and a time delay relay which will throw a switch to start the motor 25 after the lapse of a predetermined time, or after the buildup of a predetermined pressure in the lubricating oil iine 28. Instruments for accomplishing these results are well known, and the circuit therefor is not illustrated in the drawings.

Fig. 2 of the drawings shows more in detail the means for the distribution of the lubricating oil to the various gears, as well as showing the relationship of the gears with respect to the drum ill and its mounting. As shown in this figure of the drawings, the driving end of the drum 40, which may be either the feed or the discharge end, includes a heavy metal head 36 having an integral projecting hollow axial trunnion 38 having an exterior bearing surface mounted in a semicyclindrical bearing 40 comprising a part of the support M. The projecting end of the trunnion 35 includes a heavy integral annular flange 42 to which is secured a large diameter herringbone gear :24 by which the drum i0 is driven. The gear 54 meshes with a herringbone pinion gear ii) keyed, to a shaft 18, to which is also keyed a relatively large herringbone gear 56 which meshes with and is driven by a small herringbone pinion gear 52. The gear 52 may be cut integral with or keyed to the shaft 56 which is coupled to the drive shaft of the motor 20 by means of a coupling member 56. The shafts 48 and 5d are mounted in the support casing 14 and completely encased, to prevent the infiltration of dust.

The direction of rotation of the drum It is indicated by the arrow to the right in Fig. 1. From this the direction of rotation of the gears M, Q8, 56 and 52 will be apparent. Fig. 2 shows the arrangement for distributing or spraying the lubrieating oil onto the various gears and trunnion bearings. The pipe 39 terminates above the juncture of the gears 5i} and 5?. to supply lubricant directly through two spray heads at the point where the converging gear teeth meet during the rotation of the gears. On the other hand, the oil line terminates in a pair of spray nozzles directly below the juncture of the gears ie and 46. The oil line 3:; extends above the gears 64 and 58, around the gear as and terminates in a spray nozzle directly over the bearing surface of trunnion 38 at a point above the left-hand end of the bearing 59. The line 35 extends around the base Hand terminates in a slot 5i from three to six inches long in the bearing 42 under the trunnion 38 (Figs. 2 and 3). The valve 29 in line 23 is preferably used to build up a pressure of 300 lbs. per square inch in the line 35 to lift the trunnion 38 in the bearing 39. The supply of lubricant to this point prior to the starting of the gears frees the trunnion bearing 38 and insures lubrication of the bearing 518, along with oil from the line 3-3.

In many cases the bearings corresponding to the bearing 4i] become hot because of the heavy load, and they must be thoroughly lubricated and usually provided with channels for the circula tion or" cooling water. When the mill is stopped after considerable operation, and the bearings are hot, the lubricating oil has a tendency to run out or .to be forced out because of its thinness at the high bearing temperatures. Accordingly, it is important that the lubricant be supplied to the bearings prior to the starting of the gears. The importance of supplying lubricating 011 to the lines and 32 at the gear junctures, has been pointed out above. The bearings for shafts 48 and 54 may be oiled from lines 30 and 3-2 or by oil carried up by the gears.

The driving gear mechanism described above may be mounted either at the feed or at the discharge end of the mill. However, in Fig. 3, the gear arrangement is shown, for purposes of illustration, as mounted at the discharge end in connection with special means for protecting the gear system from the very fine dust which is present in material handling plants. The hollow trunnion, as shown in Fig. 3, is lined with a cylindrical sleeve member 58 having an external annual flange '69 by which it is secured to a shoulder on the projecting end of the trunnion 38. The member *5-8 extends beyond the side of the gear casing and is provided with internal helical fins (i2 arranged to convey coarse material back into the drum I0. Mills of this type can be discharged by overflow or by mechanical lifting means, but when air-swept, they usually operated in connection with an air stream which flows into the mill through the inlet end and which picks up the pulverized material produced by the mill and carries it to the outlet end to storage or to points of use. This stream of air has a tendency to carry relatively large particles of the material being reduced, and these particles are caught by the fins .62 and moved back into the drum I9 due to the rotation of the member 58 along with the drum.

Fig. 3 shows the cylindrical sleeve member 58 in detail and the fact that at each end it is provided with inwardly extending flanges, the inner flange of which engages the wear-resisting lining of the head 36. The outer flange 64 serves as a mounting for the sealing means for connectin the mill to the outlet or discharge duct or chute which conveys the air stream of pulverized material. The joint between the trunnion 38 and the gear casing is provided with a sealing member adjacentthe head 36 comprising an annular metal sealing plate fit bolted to the base It and to the casing I8 and extending at an angle out to the trunnion where it termin-ates in a packing seal at its inner edge. The gear casing also includes a projecting rotary sleeve 68 which is bolted to the flange 42 and which is substantially spaced from and surrounds the member 58. Sleeve 68 extends substantially beyond the gear wheel 4 where it is engaged by a stationary flanged sleeve member Ii! of s-shape in cross-section. This member is bolted to the outside of the base I4 and to a flange on the upper portion of the casing I8. A packing ring 7 I2 is held between the inner end of the member I0 and a flange bead near the outer end of the annular sleeve 68. The end of the sleeve 63 projects into the stationary member It and rotates therein.

,While the rotary sleeve member 68, together with the member Ill, provides a seal for the gear casing, considerable trouble has developed because of the fact thatpulverized material and dust has a tendency to get back in between the member 58 and the sealing members 68 and Eli, and work intothe gears. According to the present invention, an auxiliary seal has been provided between the outer ends of the members 58 and 16 in order to more completely eliminate the presence of dust around the member 58. Accordingly, an annular flange plate 14 is bolted to the outer. flange 64 on the member 58 and sealed thereto with a suitable gasket. The flange plate M is faced with a rub plate 16 and the two are bolted to the flange a l by means of countersunk bolts as shown. The outer edge or rim of the plate 14 slides in an annular laminated sealing joint I8 bolted to the gear casing and base It along with the outwardly extending annular flange of the member Id. The laminated seal includes a pair of relatively thin plates held against the member 10, a spacer plate of approximately the thickness of'the movable flange plate CJI I4 and a cover plate which overlaps the rim of plate I4 and the spacer plate. The spacer plate is of somewhat larger diameter than the circumference of the plate 14 so that an annular space 86 is provided for a grease-like lubricant to complete the seal. An annular deflecting flange 32 extends over the laminated seal so as to deflect any dust or fine pulverized material which may pass around the rub plate I6.

As shown in Fig. 3, the discharge end of the mill includes an upwardly extending chute 84 which projects inside ofv the annular plate 16. This projecting section of the chute includes a horizontal cylindrical portion surrounded by a rub plate assembly comprising an annular plate 86 .to which is bolted a heavy rub plate or packing ring 88, by means of countersunk bolts, as shown. A narrow packing ring 90 is also provided between the plate 86 and the horizontal cylindrical portion of the chute 84. The chute mounting includes bracket members 92 supporting a spring and pin assembly 34 for urging the plate 86 and the packing ring 88 against the rub plate 16.

As the drum II rotates, the rub plate 16 also rotates and rubs against the annular ring 88 which is urged in close engagement therewith by means of the spring units 94. These spring units are distributed around the periphery of the discharge passage 50 as to provide the best possible seal under the circumstances.

During the operation of the apparatus, the drum become overcharged with the material to be pulverized and it may fill substantially into the outlet trunnion section. The apparatus therefore includes a bl0wdown pipe 96 of substantial size for discharging the excess material; The pipe is normally closed but an operator may blow out the excess material by throwing the valve lever 98 which operates a valve member lllfl.

The feed end of the mill of the present invention is shown in some detail in Fig. 3 of the drawings, and comprises a hollow trunnion I82 resting in. a semiannular bearing I04 carried by a support Hi5. The trunnion I62 is sealed with respect to the support and the upper part of a casing surrounding the bearing, by means of an annular sealing plate or ring I I18. The outer end of the trunnion is sealed with respect to the support and upper portion of the casing by means of an annular sealing plate Hi1, which, together with the support I 86, forms a. well for lubricating oil. Lubricant is carried to the top of the trunnion by an attached annular flanged plate I I2 which rotateswith the trunnion and carries lubricant, which'is removed by a spring-pressed scraper H4. Access to the upper portion of the casing is obtained by removing cover I It.

The trunnion N32 is provided with a sleevelike lining H8 having internal helical fins for advancing material into the drum" II). An L- shaped flange I I9 on the end of the sleeve H8 is bolted to'the end of the trunnion I02 to hold plate H2 in place and to provide a bearing for plate II!) which terminates in a hooked flange serrated seal and a felt ring I2! held in place by a plate as shown. A slot I23 drains oil from the serrations into the reservoir, although most of the oil on the outside of plate H2. is caught by the L-flange thereon. The material to be pulverized is supplied to the member IIB by means of a feed chute I20 which is sealed with respect to the trunnion'and the member H8 by means of a springepressed rub sealassembly I22 of similar construction to that at the opposite end of the mill. The lubrication of the trunnion bearings may be modified from the system shown, by providing channels in the bearing 16 like, that in bearing 49, into which oil may be forced from a high pressure line connected to the line 35. The gears and bearings of the mill may be lubricated in the manner described above, entirely lubricated from the pump 22, or partly by the pump 22 and partly by lubricating oil carried up by the gears or bearings. Means may be provided in the gear casing 18 for taking lubricating oil from a high point on the gear 44 and conducting it to the various bearings such as for shafts 48 and 54.

Fig. 4 of the drawings illustrates a preferred arrangement for lubricating the bearings of the shafts 48 and 54, the showing being particularly directed to the lubrication of one end of the shaft 48. As shown, the shaft 48 is provided with a roller bearing unit I32, the inner race of, which is, held to the end of the shaft by means of a plate I34. The unit 132 is in a casing 136 which may be in or comprise a part of the casing of elements [4 and 18. The bearing 48 is enclosed by a cover plate 138. The casing 135 includes flanges I40 for retaining lubricating oil around the lower rollers of the bearing unit. These elements I40 provide a small reservoir of oil which will be present when the apparatus is started and insure proper lubrication at the beginning of the operation. Lubricant may be supplied to the bearing through a pipe I42 which may be connected to one of the lines 30 or 32, or to a drainage system for oil elevated by the gear 44. Excess oil may overflow either of the flanges H39 and drain back into the reservoir in the gear casing.

The improved mill of the present invention may include other modifications in the structure and arrangement of the various parts, as will be understood by those skilled in the art from the foregoing description. The mill may include an oil sealed breather for the gear casing as at M4, Fig. 1, so that expansion and contraction of the air in the gear casing may be taken care of without admission of dust. It is to be understood that the mill is of general application and that it may be used either for wet or dry grinding by means of balls, rods, or other loose grinding elements. Furthermore, the mill may be used for grinding various kinds of material, such as cement, slurries, ores, chemicals, paints and other materials.

What I claim as new is:

1. In a heavy grinding mill for the reduction of materials including a rotary drum containing loose grinding elements of the type of tubes, rods and balls, a rotary drum having hollow axial end trunnions projecting therefrom and mounted in bearings in supports, the trunnions having an outer bearing surface, a. reduction gear system connected to one of said trunnions, motor means for driving the gear system to rotate the drum, a gear casing surrounding said gear system and the trunnion "bearing thereat, a lubricating oil reservoir in the lower part of said casing, and a sealing means between the rotary trunnion associated with the gear system and the gear casing for excluding dust from the gear system, the improvement comprising a lubricating oil pump, means for conducting oil from the reservoir to the pump, a slot in the upper surface of the support bearing beneath the lower portionof the bearing surface of the trunnion in the gear casing,

means for conducting lubricating oil from the pump to said slot whereby lubricating oil is forced between the bearing surface of the hollow trunnion and the surface of its support bearing in such a manner as to lift the trunnion and thor oughly lubricate the bearing surfaces prior to starting the rotation of the mill, an oil delivery nozzle directed toward the bearing surface of the trunnion in the casing, means for conducting lubricating oil from said pump to said oil delivery nozzle, oil spraying means associated with the inter-meshing gears of said system at their juncture points where the gear teeth move toward each other when the gears are rotated, means for conducting lubricating oil from said pump to said oil spraying means, and a separate motor means for operating said pump whereby the gears and bearings in the casing may be lubricated before starting rotation of the drum.

2. In a heavy grinding mill for the reduction of materials including a rotary drum containing loose grinding elements of the type of tubes, rods and balls, a rotary drum having hollow axial end trunnions projecting therefrom and mounted in bearings in sup-ports, the trunnions having an outer bearing surface, a reduction gear system connected to one of said trunnions, motor means for driving the gear system to rotate the drum, a gear casing surrounding said gear system and the trunnion bearing thereat, a lubricating oil reservoir in the lower part of said casing, and a sealing means between the rotary trunnion associated with the gear system and the gear casing for excluding dust from the gear system, the improvement comprising a lubricating oil pump, means for conducting oil from the reservoir to the pump, a slot in the upper surface of the support bearing beneath the lower portion of the bearing surface of the trunnion in the gear casing, means for conducting lubricating oil from the pump to said slot whereby lubricating oil is forced between the bearing surface of the hollow trunnion and the surface of its support bearing in such manner as to lift the trunnion and thoroughly lubricate the bearing surfaces prior to starting the rotation of the mill, oil spraying means associated with the inter-meshing gears of said system at their juncture points on the sides where the gear teeth move toward each other when the gears are rotated, means for conducting lubricating oil from said pump to said oil spraying means, and a separate motor means for operating said pump whereby the gears and bearings in the casing may be lubricated before starting rotation of the drum.

JOSEPH E. KENNEDY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,619,886 Ross Dec. 14, 1925 1,993,588 Blanchard Mar. 5, 1935 2,062,250 Mol-ler Nov. 24, 1936 2,160,778 Dall May 30, 1939 2,178,542 Ott Nov. 7, 1939 2,299,825 Kennedy Oct. 2'7, 1942 FOREIGN PATENTS Number Country Date 331,734 Germany Jan. 14, 1921 86,618 Switzerland Oct. 1. 1920 

